diff --git a/app/controllers/admin/shop_orders_controller.rb b/app/controllers/admin/shop_orders_controller.rb
index 89b6d20e..729be5f5 100644
--- a/app/controllers/admin/shop_orders_controller.rb
+++ b/app/controllers/admin/shop_orders_controller.rb
@@ -339,4 +339,31 @@ def assign_user
       redirect_to admin_shop_orders_path(view: "fulfillment"), alert: "Failed to assign order"
     end
   end
+
+  def cancel_hcb_grant
+    authorize :admin, :manage_users?
+    @order = ShopOrder.find(params[:id])
+
+    unless @order.shop_card_grant.present?
+      redirect_to admin_shop_order_path(@order), alert: "This order has no HCB grant to cancel"
+      return
+    end
+
+    grant = @order.shop_card_grant
+    begin
+      HCBService.cancel_card_grant!(hashid: grant.hcb_grant_hashid)
+
+      PaperTrail::Version.create!(
+        item_type: "ShopOrder",
+        item_id: @order.id,
+        event: "hcb_grant_canceled",
+        whodunnit: current_user.id,
+        object_changes: { hcb_grant_hashid: grant.hcb_grant_hashid, canceled_by: current_user.display_name }.to_json
+      )
+
+      redirect_to admin_shop_order_path(@order), notice: "HCB grant canceled successfully"
+    rescue => e
+      redirect_to admin_shop_order_path(@order), alert: "Failed to cancel HCB grant: #{e.message}"
+    end
+  end
 end
diff --git a/app/controllers/admin/users_controller.rb b/app/controllers/admin/users_controller.rb
index 7dfc94ca..852ea294 100644
--- a/app/controllers/admin/users_controller.rb
+++ b/app/controllers/admin/users_controller.rb
@@ -306,6 +306,44 @@ def update
     redirect_to admin_user_path(@user)
   end
 
+  def cancel_all_hcb_grants
+    authorize :admin, :manage_users?
+    @user = User.find(params[:id])
+
+    grants = @user.shop_card_grants.where.not(hcb_grant_hashid: nil)
+
+    if grants.empty?
+      redirect_to admin_user_path(@user), alert: "This user has no HCB grants to cancel"
+      return
+    end
+
+    canceled_count = 0
+    errors = []
+
+    grants.find_each do |grant|
+      begin
+        HCBService.cancel_card_grant!(hashid: grant.hcb_grant_hashid)
+        canceled_count += 1
+      rescue => e
+        errors << "Grant #{grant.hcb_grant_hashid}: #{e.message}"
+      end
+    end
+
+    PaperTrail::Version.create!(
+      item_type: "User",
+      item_id: @user.id,
+      event: "all_hcb_grants_canceled",
+      whodunnit: current_user.id,
+      object_changes: { canceled_count: canceled_count, canceled_by: current_user.display_name }.to_json
+    )
+
+    if errors.any?
+      redirect_to admin_user_path(@user), alert: "Canceled #{canceled_count} grants, but #{errors.count} failed: #{errors.first}"
+    else
+      redirect_to admin_user_path(@user), notice: "Successfully canceled #{canceled_count} HCB grant(s)"
+    end
+  end
+
   private
 
   def user_params
diff --git a/app/models/user.rb b/app/models/user.rb
index 7821cdaa..b54d4f03 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -52,6 +52,7 @@ class User < ApplicationRecord
   has_many :projects, through: :memberships
   has_many :hackatime_projects, class_name: "User::HackatimeProject", dependent: :destroy
   has_many :shop_orders, dependent: :destroy
+  has_many :shop_card_grants, dependent: :destroy
   has_many :votes, dependent: :destroy
   has_many :reports, class_name: "Project::Report", foreign_key: :reporter_id, dependent: :destroy
   has_many :likes, dependent: :destroy
diff --git a/app/views/admin/shop_orders/show.html.erb b/app/views/admin/shop_orders/show.html.erb
index 79e0597e..8b8bdbf3 100644
--- a/app/views/admin/shop_orders/show.html.erb
+++ b/app/views/admin/shop_orders/show.html.erb
@@ -241,6 +241,18 @@
     <h2>Card Grant</h2>
     <div class="info-rows">
       <div><b>Card Grant ID:</b> <%= @order.shop_card_grant_id %></div>
+      <% if @order.shop_card_grant&.hcb_grant_hashid.present? %>
+        <div><b>HCB Grant ID:</b> <%= @order.shop_card_grant.hcb_grant_hashid %></div>
+        <div>
+          <%= link_to "View on HCB", @order.shop_card_grant.hcb_url, target: "_blank", class: "btn-primary", style: "margin-right: 0.5rem;" %>
+          <% if current_user.admin? && @order.fulfilled? %>
+            <form method="post" action="<%= cancel_hcb_grant_admin_shop_order_path(@order) %>" style="display: inline;">
+              <%= hidden_field_tag :authenticity_token, form_authenticity_token %>
+              <button type="submit" class="btn-danger" onclick="return confirm('Are you sure you want to cancel this HCB grant? This cannot be undone.')">Cancel HCB Grant</button>
+            </form>
+          <% end %>
+        </div>
+      <% end %>
     </div>
   </div>
 <% end %>
diff --git a/app/views/admin/users/show.html.erb b/app/views/admin/users/show.html.erb
index be848400..a1d4ef3f 100644
--- a/app/views/admin/users/show.html.erb
+++ b/app/views/admin/users/show.html.erb
@@ -140,6 +140,25 @@
         <% end %>
       <% end %>
 
+      <% if current_user.admin? %>
+        <% has_grants = @user.shop_card_grants.where.not(hcb_grant_hashid: nil).exists? %>
+        <button type="button" onclick="document.getElementById('cancel-grants-modal').showModal()" class="btn-danger slim" <%= 'disabled style="opacity: 0.5; cursor: not-allowed;"'.html_safe unless has_grants %>>
+          🚫 Cancel All HCB Grants
+        </button>
+        <% if has_grants %>
+          <%= render layout: "shared/modal", locals: { id: "cancel-grants-modal", title: "Cancel All HCB Grants", description: "This will cancel ALL HCB grants for #{@user.display_name}. This action cannot be undone!" } do %>
+            <form action="<%= cancel_all_hcb_grants_admin_user_path(@user) %>" method="post">
+              <%= hidden_field_tag :authenticity_token, form_authenticity_token %>
+              <p style="color: #ef4444; font-weight: bold;">⚠️ Warning: This will cancel <%= @user.shop_card_grants.where.not(hcb_grant_hashid: nil).count %> grant(s).</p>
+              <div class="modal__actions">
+                <button type="submit" class="btn-danger slim">Confirm Cancel All Grants</button>
+                <button type="button" onclick="document.getElementById('cancel-grants-modal').close()" class="btn-secondary slim">Cancel</button>
+              </div>
+            </form>
+          <% end %>
+        <% end %>
+      <% end %>
+
       <% if policy(:admin).ban_users? %>
         <% if @user.banned? %>
           <%= button_to "🔓 Unban User", unban_admin_user_path(@user), method: :post, class: "btn-primary slim" %>
diff --git a/config/routes.rb b/config/routes.rb
index efb75471..80a32351 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -186,6 +186,7 @@ def self.matches?(request)
          post :adjust_balance
          post :ban
          post :unban
+         post :cancel_all_hcb_grants
          post :impersonate
        end
        collection do
@@ -216,6 +217,7 @@ def self.matches?(request)
         post :mark_fulfilled
         post :update_internal_notes
         post :assign_user
+        post :cancel_hcb_grant
       end
     end
     resources :audit_logs, only: [ :index, :show ]